I sometimes, still use IRC, mostly in Freenode. However sometimes I enter in Bulgarian IRC Network UniBG via IRC access node irc.spnet.net
Problem is by default irssi does not recognize Cyrillic so Bulgarian, Russian, Ukrainian and other Slavonic languages are unreadable. Same goes also for Chineese, Arabic and other "unstandard" characters. Hence from to make irssi support cyrillic, I had to launch it once:
linux:~$ irssi
And then type in it:
/set recode_fallback cp1251
/set recode_out_default_charset cp1251
/set recode_transliterate off
/set recode_autodetect_utf8 on
/set term_charset utf-8
/exit
linux:~$ irssi
After next irssi Launch Cyrillic displays proper Cyrillic letters.